Electroplating composite substrates

Abstract

An electrolyte employed to selectively deposit a tin or tin alloy film on a composite substrate. A method for depositing the tin or tin alloy on the composite substrate also is described.

1. A composition consisting essentially of one or more sources of tin, the source of tin consists of stannous organic sulfonate, stannous sulfate, stannous gluconate, stannous citrate, stannous lactate, stannous halide or mixtures thereof; at least one surfactant which is an alcohol ethoxylate; one or more aromatic diols; one or more conductivity agents, the conductivity agents consist of alkali metal sulfates, alkali metal alkanesulfonates, alkali metal chlorides, ammonium sulfate, sulfuric acid, citric acid, sodium acetate, sodium carbonate, diluent soluble salts of citrates, lactates, and gluconates, and potassium pyrophosphate; and one or more compounds having a general formula:
   HOOCBCOOH  (1) 
 
       where B is a chemical bond or is —(CH 2 ) n — and n is an integer of from 1 to 4, a salt of the compound or an ester thereof, the compound, salt or ester thereof is in an amount of from 15 gm/L to 55 gm/L. 
     
     
       2. The composition of  claim 1 , wherein the alcohol ethoxylate has chain lengths of C 8  to C 22  and ethoxylation is from 1 to 30 moles per mole of alcohol. 
     
     
       3. The composition of  claim 1 , wherein the pH of the composition ranges from 1 to 6. 
     
     
       4. The composition of  claim 1 , further consisting essentially of one or more imidazoline compounds. 
     
     
       5. The composition of  claim 1 , wherein the compound of formula (1) is malonic acid, glutaric acid or salts thereof. 
     
     
       6. The composition of ciaim  1 , wherein the aromatic diols are 1,2-benzenediol, methyl-1,4-benzenediol, cyclohexyl-1,4-benzenediol, phenyl-1,4-benzenediol, 1,2-naphthalenediol, 1,4-naphthalenediol or mixtures thereof. 
     
     
       7. The composition of  claim 1 , wherein the aromatic diols are in amounts of 0.05 gm/L to 10 gm/L. 
     
     
       8. The composition of  claim 7 , wherein the aromatic diols are in amounts of 0.1 gm/L to 2 gm/L. 
     
     
       9. The composition of  claim 1 , wherein the conductivity agents are alkali metal sulfates. 
     
     
       10. The composition of  claim 1 , wherein the compound, salt or ester thereof of general formula (1) ranges from 20 g/L to 45 g/L. 
     
     
       11. The composition of  claim 1 , wherein the composition has a pH of 2 to 4. 
     
     
       12. A method comprising:
 a) contacting a composite substrate with a composition consisting essentially of one or more sources of tin, the source of tin consists of stannous organic sulfonate, stannous sulfate, stannous gluconate, stannous citrate, stannous lactate, or stannous halide; one or more aromatic diols; one or more conductivity agents, the conductivity agents consist of alkali metal sulfates, alkali metal alkanesulfonates, alkali metal chlorides, ammonium sulfate, sulfuric acid, citric acid, sodium acetate, sodium carbonate, diluent soluble salts of citrates, lactates, and gluconates, and potassium pyrophosphate; and at least one surfactant which is an alcohol ethoxylate; arid one or more compounds having a general formula:
   HOOCBCOOH  (1) 
 
 where B is a chemical bond or is —(CH 2 ) n — and n is an integer of from 1 to 4, a salt or ester thereof the compound, salt or ester thereof is in an amount of from 15 gm/L to 55 gm/L; and 
 b) generating an electrical current through the composition to selectively deposit a tin or tin alloy film on a metal portion of the composite substrate. 
 
     
     
       13. The method of  claim 12 , wherein a non-metal portion of the composite substrate is a ceramic. 
     
     
       14. The method of  claim 12 , wherein the compound of formula (1) is malonic acid, glutaric acid or salts thereof. 
     
     
       15. A method comprising coating a base metal electrode of a composite substrate with a conductive paste; firing the conductive paste; electroplating a base metal or base metal alloy on the fired conductive paste; and electroplating a tin or tin alloy on the base metal or base metal alloy using a tin or tin alloy composition consisting essentially of one or more sources of tin, the source of tin consists of stannous organic sulfonate, stannous sulfate, stannous gluconate, stannous citrate, stannous lactate, stannous halide or mixtures thereof; at least one surfactant which is an alcohol ethoxylate; one or more aromatic diols; one or more conductivity agents, the conductivity agents consist of alkali metal sulfates, alkali metal alkanesulfonates, alkali metal chlorides, ammonium sulfate, sulfuric acid, citric acid, sodium acetate, sodium carbonate, diluent soluble salts or citrates, lactates, and gluconates, and potassium pyrophosphate; and one or more compounds having a formula:
   HOOCBCOOH  (1) 
 
       where B is a chemical bond or (—CH 2 —) n  and n is an integer of from 1 to 4, a salt of the compound or an ester thereof, the compound, salt or ester thereof is in an amount of from 15 gm/L to 55 gm/L. 
     
     
       16. The method of  claim 15 , wherein the tin or tin alloy composition further consisting essentially of an imidazoline compound.